9/20/24, 9:28 25. Electrical circuit theory (Inglés) autor Toyota Technical
AM Training
Section 1
Electrical Circuit
Theory
Learning
1. Review the basic electrical concepts of voltage, amperage, and
Objectives:
resistance.
2. Review the components of a basic automotive electrical circuit.
3. Introduce basic wiring diagram symbols.
4. Review the characteristics of voltage, amperage, and resistance in
series and parallel circuits, showing how they are used when
diagnosing electrical problems.
5. Show how series−parallel circuits are used on the vehicle.
6. Introduce the basic electrical diagnostic tools.
Body Electrical Diagnosis - Course L652 1
about:bl 1/
,9/20/24, 9:28 25. Electrical circuit theory (Inglés) autor Toyota Technical
AM Training
Section 1
2 TOYOTA Technical Training
about:bl 2/
,9/20/24, 9:28 25. Electrical circuit theory (Inglés) autor Toyota Technical
AM Training
Electrical Circuit Theory
Introducti The first step in being able to effectively diagnose electrical problems is
on to have a good understanding of basic electrical principles. These
concepts were covered in depth in the L623 course. In this course, we
will be reviewing each of them with emphasis to their on−car
applications and how these concepts are applied when you are
diagnosing an electrical problem.
Electrica
l Circuit
Diagnosis
Course L623
Course L623 covered
the “basics” of
electrical. This course
will expand on those
concepts and apply
them directly to the on-
car diagnostic process.
Voltag Simply put, think of voltage as electrical pressure or pressure
e
differential. The difference in pressure that makes any hydraulic pump
work is virtually the same for electrons. The pressure differential
provided by the positive and negative terminals of the battery causes
the electrons in a conductor to move when the two terminals are
connected together.
This movement or flow of electrons is used to perform useful work.
Whenever work is done, pressure is used up. We can measure where
work is done in an electrical circuit by measuring where voltage is used
up.
Voltage
as Pressure
Like the
pressure/suction
that a pump
provides a fluid, a
battery or alternator
provides for an
electrical circuit.
Body Electrical Diagnosis - Course L652 3
about:bl 3/
, 9/20/24, 9:28 25. Electrical circuit theory (Inglés) autor Toyota Technical
AM Training
Section 1
When working with on−car electrical problems, there are two
different methods of voltage measurement. A Technician can either
measure an open circuit voltage or a voltage drop. Open circuit voltage
is measured when there is no current flow through the circuit. A
voltage drop is
measured dynamically while there is current flow through the circuit.
Both open circuit voltage and voltage drop testing have their place in the
diagnostic process. Information from each measurement can be helpful if
used appropriately. These two measurements will be discussed in more
detail in the Electrical Diagnostic Tools section of this course.
Measuring Open
Circuit Voltage
This measurement tells
you if there is voltage
present at a terminal.
It cannot tell you if
there is any circuit
resistance up to that
point.
Measuring
Voltage Drop
This measurement
can only be done if
there is current flow in
the circuit. It
accurately tells you
how much voltage is
actually available at
the load, or the
amount of voltage lost
across connections or
wiring on either the
ground
or power side of the circuit.
4 TOYOTA Technical Training
about:bl 4/
AM Training
Section 1
Electrical Circuit
Theory
Learning
1. Review the basic electrical concepts of voltage, amperage, and
Objectives:
resistance.
2. Review the components of a basic automotive electrical circuit.
3. Introduce basic wiring diagram symbols.
4. Review the characteristics of voltage, amperage, and resistance in
series and parallel circuits, showing how they are used when
diagnosing electrical problems.
5. Show how series−parallel circuits are used on the vehicle.
6. Introduce the basic electrical diagnostic tools.
Body Electrical Diagnosis - Course L652 1
about:bl 1/
,9/20/24, 9:28 25. Electrical circuit theory (Inglés) autor Toyota Technical
AM Training
Section 1
2 TOYOTA Technical Training
about:bl 2/
,9/20/24, 9:28 25. Electrical circuit theory (Inglés) autor Toyota Technical
AM Training
Electrical Circuit Theory
Introducti The first step in being able to effectively diagnose electrical problems is
on to have a good understanding of basic electrical principles. These
concepts were covered in depth in the L623 course. In this course, we
will be reviewing each of them with emphasis to their on−car
applications and how these concepts are applied when you are
diagnosing an electrical problem.
Electrica
l Circuit
Diagnosis
Course L623
Course L623 covered
the “basics” of
electrical. This course
will expand on those
concepts and apply
them directly to the on-
car diagnostic process.
Voltag Simply put, think of voltage as electrical pressure or pressure
e
differential. The difference in pressure that makes any hydraulic pump
work is virtually the same for electrons. The pressure differential
provided by the positive and negative terminals of the battery causes
the electrons in a conductor to move when the two terminals are
connected together.
This movement or flow of electrons is used to perform useful work.
Whenever work is done, pressure is used up. We can measure where
work is done in an electrical circuit by measuring where voltage is used
up.
Voltage
as Pressure
Like the
pressure/suction
that a pump
provides a fluid, a
battery or alternator
provides for an
electrical circuit.
Body Electrical Diagnosis - Course L652 3
about:bl 3/
, 9/20/24, 9:28 25. Electrical circuit theory (Inglés) autor Toyota Technical
AM Training
Section 1
When working with on−car electrical problems, there are two
different methods of voltage measurement. A Technician can either
measure an open circuit voltage or a voltage drop. Open circuit voltage
is measured when there is no current flow through the circuit. A
voltage drop is
measured dynamically while there is current flow through the circuit.
Both open circuit voltage and voltage drop testing have their place in the
diagnostic process. Information from each measurement can be helpful if
used appropriately. These two measurements will be discussed in more
detail in the Electrical Diagnostic Tools section of this course.
Measuring Open
Circuit Voltage
This measurement tells
you if there is voltage
present at a terminal.
It cannot tell you if
there is any circuit
resistance up to that
point.
Measuring
Voltage Drop
This measurement
can only be done if
there is current flow in
the circuit. It
accurately tells you
how much voltage is
actually available at
the load, or the
amount of voltage lost
across connections or
wiring on either the
ground
or power side of the circuit.
4 TOYOTA Technical Training
about:bl 4/
